Left ventricular noncompaction (LVNC) is a cardiomyopathy caused by an arrest of normal myocardial development during fetal life. During normal heart development, the embryonic myocardium is a loose spongy network of muscle fibres that gradually compacts to form the smooth, dense ventricular wall. In LVNC, this compaction process is incomplete, leaving prominent trabeculae (muscular ridges) and deep recesses on the inner surface of the left ventricle. This gives the left ventricle a characteristic sponge-like appearance on echocardiography or cardiac MRI.
LVNC can occur in isolation or alongside other congenital heart defects, and it may be associated with mutations in genes encoding sarcomeric proteins, ion channels, or cytoskeletal proteins. There is significant overlap with other cardiomyopathies (particularly dilated cardiomyopathy), and some experts debate whether LVNC represents a distinct disease or a morphological trait with varying clinical significance.
The clinical presentation of LVNC varies widely. Some people have normal left ventricular function and no symptoms throughout their lives. Others develop heart failure, thromboembolic events (clots can form in the deep trabecular recesses and embolise to the brain or body), arrhythmias including ventricular tachycardia and ventricular fibrillation, and sudden cardiac arrest. LVNC is a recognised cause of sudden death, particularly in young people.
Management is guided by the clinical presentation and degree of ventricular dysfunction. Heart failure is treated with standard medications. Anticoagulation is recommended when left ventricular function is significantly impaired. ICD implantation may be considered for those with reduced ejection fraction or a personal or family history of sudden cardiac death. Specialist follow-up and family screening are recommended.
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